A Trackback is a type of Linkback – a method for Web authors to request notification when somebody links to one of their documents. This enables authors to keep track of who is linking, and so referring, to their articles. There are three methods of Linkback – Refback, Trackback and Pingback – and they differ in how they accomplish the task.
Trackback might also refer colloquially to items within a section upon the linked page that display the received notifications, usually along with a reciprocal link. Also, the word Trackback is often used colloquially to mean any kind of Linkback.
So, when you reference a post on someone else’s blog in one of your posts, using the trackback URL will ensure the other blog author will be notified. This notification will generally appear in the comments section of their post.
For more details – see the Ultimate Trackback Help Guide.
See more definitions in the Definitive Guide to Blogging Terms.